Conductive Structures Including Titanium-Tungsten Base Layers

ABSTRACT

Methods may be provided for forming an electronic device including a substrate, a conductive pad on the substrate, and an insulating layer on the substrate wherein the insulating layer has a via hole therein exposing a portion of the conductive pad. In particular, a conductive structure may be formed on the insulating layer and on the exposed portion of the conductive pad. The conductive structure may include a base layer of titanium-tungsten (TiW) and a conduction layer of at least one of aluminum and/or copper. Moreover, the base layer of the conductive structure may be between the conduction layer and the insulating layer. Related devices are also discussed.

RELATED APPLICATIONS

This application claims the benefit of priority as a divisional of U.S.patent application Ser. No. 10/879,411 filed on Jun. 29, 2004, whichclaims the benefit of priority from U.S. Provisional Patent ApplicationNo. 60/490,340 filed on Jul. 25, 2003, and from U.S. Provisional PatentApplication No. 60/507,587 filed on Oct. 1, 2003. The disclosures of allof the above referenced Patent Applications are hereby incorporatedherein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to the field of integrated circuits andmore particularly to methods of forming conductive structures forintegrated circuit devices and related structures.

BACKGROUND OF THE INVENTION

High performance microelectronic devices often use solder balls orsolder bumps for electrical interconnection to other microelectronicdevices. For example, a very large scale integration (VLSI) chip may beelectrically connected to a circuit board or other next level packagingsubstrate using solder balls or solder bumps. This connection technologyis also referred to as “Controlled Collapse Chip Connection—C4” or“flip-chip” technology, and will be referred to herein as solder bumps.

According to solder bump technology developed by IBM, solder bumps areformed by evaporation through openings in a shadow mask which is clampedto an integrated circuit wafer. For example, U.S. Pat. No. 5,234,149entitled “Debondable Metallic Bonding Method” to Katz et al. disclosesan electronic device with chip wiring terminals and metallizationlayers. The wiring terminals are typically essentially aluminum, and themetallization layers may include a titanium or chromium localizedadhesive layer, a co-deposited localized chromium copper layer, alocalized wettable copper layer, and a localized gold or tin cappinglayer. An evaporated localized lead-tin solder layer is located on thecapping layer.

Solder bump technology based on an electroplating method has also beenactively pursued. The electroplating method is particularly useful forlarger substrates and smaller bumps. In this method, an “under bumpmetallurgy” (UBM) layer is deposited on a microelectronic substratehaving contact pads thereon, typically by evaporation or sputtering. Acontinuous under bump metallurgy layer is typically provided on the padsand on the substrate between the pads to allow current flow duringsolder plating.

An example of an electroplating method with an under bump metallurgylayer is discussed in U.S. Pat. No. 5,162,257 entitled “solder BumpFabrication Method” to Yung and assigned to the assignee of the presentapplication. In this patent, the under bump metallurgy layer includes achromium layer adjacent the substrate and pads, a top copper layer whichacts as a solderable metal, and a phased chromium/copper layer betweenthe chromium and copper layers. The base of the solder bump is preservedby converting the under bump metallurgy layer between the solder bumpand contact pad into an intermetallic of the solder and the solderablecomponent of the under bump metallurgy layer.

An example of a redistribution routing conductor is discussed in U.S.Pat. No. 6,389,691 entitled “Methods For Forming IntegratedRedistribution Routing Conductors And Solder Bumps” to Rinne et al. andassigned to the assignee of the present application. In this patent, aredistribution routing conductor can be integrally formed together withan associated solder bump.

Notwithstanding the methods and structures discussed above, therecontinues to exist a need in the art for improved interconnectionstructures.

SUMMARY OF THE INVENTION

According to embodiments of the present invention, methods may beprovided for forming an electronic device including a substrate, aconductive pad on the substrate, and an insulating layer on thesubstrate wherein the insulating layer has a via hole therein exposing aportion of the conductive pad. More particularly, a conductive structuremay be formed on the insulating layer and on the exposed portion of theconductive pad. The conductive structure may include a base layerincluding titanium-tungsten (TiW) and a conduction layer including atleast one of aluminum and/or copper. Moreover, the base layer of theconductive structure is between the conduction layer and the insulatinglayer.

In addition, forming the conductive structure may include forming alayer of titanium-tungsten on the insulating layer and on the exposedportions of the conductive pad, and forming the conduction layerincluding at least one of aluminum and/or copper on the layer oftitanium-tungsten so that portions of the titanium-tungsten layer areexposed. After forming the conduction layer, portions of the layer oftitanium-tungsten exposed by the conduction layer may be removed. Moreparticularly, removing portions of the layer of titanium-tungsten mayinclude etching the layer of titanium-tungsten using hydrogen peroxide.In an alternative, removing portions of the layer of titanium-tungstenmay include etching the layer of titanium-tungsten using a mixtureincluding hydrogen peroxide, potassium sulfate, benzotriazole, andsulfo-salicylic acid.

The base layer of the conductive structure may include a lip extendingbeyond the conduction layer of the conductive structure, and/or theconductive pad may include at least one of aluminum and/or copper. Asecond insulating layer may be formed on the conductive structure and onthe first insulating layer so that the conductive structure is betweenthe first and second insulating layers, and a second via hole in thesecond insulating layer may expose a portion of the conductivestructure. Moreover, the first and second via holes may be offset. Aninterconnection structure (such as a solder bump) may also be formed onthe exposed portion of the conductive structure, and an under bumpmetallurgy layer may be formed between the interconnection structure andthe exposed portion of the conductive structure.

The conduction layer of the conductive structure may include an aluminumlayer, and the conduction layer may also include a titanium layerbetween the aluminum layer and the base layer of the conductivestructure. A portion of the conductive pad may be exposed between theinsulating layer and the conductive structure. Moreover, the insulatinglayer may include at least one of benzocyclobutene, polyimide, siliconoxide, silicon nitride, and/or silicon oxynitride.

According to additional embodiments of the present invention, methodsmay be provided for forming an electronic device including a substrateand an insulating layer on the substrate. More particularly, aconductive structure may be formed on the insulating layer, and theconductive structure may include a base layer includingtitanium-tungsten (TiW) and a conduction layer including at least one ofaluminum and/or copper. Moreover, the base layer of the conductivestructure may be between the conduction layer and the insulating layer,and the base layer of the conductive structure may include a lipextending beyond the conduction layer of the conductive structure.

Forming the conductive structure on the insulating layer may includeforming a layer of titanium-tungsten on the insulating layer, and afterforming the layer of titanium-tungsten, the conduction layer may beformed on the layer of titanium-tungsten so that portions of the layerof titanium-tungsten are exposed. After forming the conduction layer,portions of the layer of titanium-tungsten exposed by the conductionlayer may be removed. More particularly, removing portions of the layerof titanium-tungsten may include etching the layer of titanium-tungstenusing hydrogen peroxide. In an alternative, removing portions of thelayer of titanium-tungsten may include etching the layer oftitanium-tungsten using a mixture including hydrogen peroxide, potassiumsulfate, benzotriazole, and sulfo-salicylic acid.

The electronic device may include a conductive pad on the substrate, theinsulating layer may have a via hole therein exposing a portion of theconductive pad, and forming the conductive structure may include formingthe conductive structure on the insulating layer and on exposed portionsof the conductive pad. More particularly, the conductive pad may includeat least one of aluminum and/or copper. In addition, a portion of theconductive pad may be exposed between the insulating layer and theconductive structure.

A second insulating layer may be formed on the conductive structure andon the first insulating layer so that the conductive structure isbetween the first and second insulating layers. In addition, a secondvia hole may be formed in the second insulating layer exposing a portionof the conductive structure. Moreover, an interconnection structure(such as a solder bump) may be formed on the exposed portion of theconductive structure, and an under bump metallurgy layer may be formedbetween the interconnection structure and the exposed portion of theconductive structure.

The conduction layer of the conductive structure may include an aluminumlayer, and the conduction layer may also include a titanium layerbetween the aluminum layer and the base layer of the conductivestructure. In addition, the insulating layer may include at least one ofbenzocyclobutene, polyimide, silicon oxide, silicon nitride, and/orsilicon oxynitride.

According to still additional embodiments of the present invention, anelectronic device may include a substrate, a conductive pad, aninsulating layer, and a conductive structure on the insulating layer.The conductive pad may be on the substrate, and the insulating layer maybe on the substrate and on the conductive pad. In addition, theinsulating layer may have a via hole therein exposing a portion of theconductive pad. The conductive structure may be on the insulating layerand on the exposed portion of the conductive pad. More particularly, theconductive structure may include a base layer comprisingtitanium-tungsten (TiW) and a conduction layer comprising at least oneof aluminum and/or copper. Moreover, the base layer of the conductivestructure may be between the conduction layer and the insulating layer.The base layer of the conductive structure may include a lip extendingbeyond the conduction layer of the conductive structure, and/or theconductive pad may include at least one of aluminum and/or copper.

In addition, a second insulating layer may be provided on the conductivestructure and on the first insulating layer so that the conductivestructure is between the first and second insulating layers. Moreover,the second insulating layer may have a second via hole therein exposinga portion of the conductive structure wherein the first and second viaholes are offset. An interconnection structure (such as a solder bump)may be provided on the exposed portion of the conductive structure, andan under bump metallurgy layer may be provided between theinterconnection structure and the exposed portion of the conductivestructure.

The conduction layer of the conductive structure may include an aluminumlayer, and the conduction layer may also include a titanium layerbetween the aluminum layer and the base layer of the conductivestructure. A portion of the conductive pad may be exposed between theinsulating layer and the conductive structure, and/or the insulatinglayer may include at least one of benzocyclobutene, polyimide, siliconoxide, silicon nitride, and/or silicon oxynitride.

According to yet additional embodiments of the present invention, anelectronic device may include a substrate, an insulating layer on thesubstrate, and a conductive structure on the insulating layer. Theconductive structure may include a base layer includingtitanium-tungsten (TiW) and a conduction layer including at least one ofaluminum and/or copper. Moreover, the base layer of the conductivestructure may be between the conduction layer and the insulating layer,and the base layer of the conductive structure may include a lipextending beyond the conduction layer of the conductive structure.

The electronic device may also include a conductive pad on thesubstrate, and the insulating layer may have a via hole therein exposinga portion of the conductive pad. In addition, a portion of theconductive structure may be on the exposed portion of the conductivepad. The conductive pad may include at least one of aluminum and/orcopper, and a portion of the conductive pad may be exposed between theinsulating layer and the conductive structure.

In addition, a second insulating layer may be provided on the conductivestructure and on the first insulating layer so that the conductivestructure is between the first and second insulating layers, and thesecond insulating layer may have a second via hole therein exposing aportion of the conductive structure. In addition, an interconnectionstructure (such as a solder bump) may be provided on the exposed portionof the conductive structure, and an under bump metallurgy layer may beprovided between the interconnection structure and the exposed portionof the conductive structure.

Moreover, the conduction layer of the conductive structure may be analuminum layer, and the conduction layer may also include a titaniumlayer between the aluminum layer and the base layer of the conductivestructure. In addition, the insulating layer may include at least one ofbenzocyclobutene, polyimide, silicon oxide, silicon nitride, and/orsilicon oxynitride.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1, 2A-B, 3, and 4 are cross-sectional views illustrating steps offorming conductive structures and resulting conductive structuresaccording to embodiments of the present invention.

FIGS. 5-9 are cross-sectional views illustrating steps of methods offorming conductive structures and resulting conductive structuresaccording to additional embodiments of the present invention.

FIGS. 10-13 are photographs illustrating conductive structures accordingto yet additional embodiments of the present invention.

DETAILED DESCRIPTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. In thedrawings, thicknesses of layers and regions are exaggerated for clarity.Like numbers refer to like elements throughout.

It will be understood that when an element such as a layer, region orsubstrate is referred to as being “on” another element, it can bedirectly on the other element, or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” another element, there are no intervening elements present. Also,when an element is referred to as being “bonded” to another element, itcan be directly bonded to the other element or intervening elements maybe present. In contrast, when an element is referred to as being“directly bonded” to another element, there are no intervening elementspresent. It will also be understood that when an element is referred toas being “connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. Finally, the term “directly” means that there are nointervening elements.

According to embodiments of the present invention, a conductivestructure including an aluminum and/or copper layer may be provided onan organic and/or an inorganic insulating passivation layer. Theconductive structure, for example, may be used as a redistributionrouting line providing electrical connectivity between an input/outputpad on a substrate and an interconnection structure (such as a solderbump) offset from the input/output pad. Conductive lines and solderbumps according to embodiments of the present invention may be used, forexample, to provide structures for flip chip processing. In otheralternatives, a conductive line according to embodiments of the presentinvention may provide interconnection between two conductiveinput/output pads, between a conductive input/output pad and anotherconductive line, and/or between two interconnection structures.

Embodiments of the present invention are described herein with referenceto cross-section illustrations that are schematic illustrations ofidealized embodiments of the present invention. As such, variations fromthe shapes of the illustrations as a result, for example, ofmanufacturing techniques and/or tolerances, are to be expected. Thus,embodiments of the present invention should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, a conductive layer illustrated as arectangle may, typically, have rounded or curved features. Thus, theregions illustrated in the figures are schematic in nature and theirshapes are not intended to illustrate the precise shape of a region of adevice and are not intended to limit the scope of the present invention.

An electronic structure according to embodiments of the presentinvention is illustrated in FIG. 4. As shown in FIG. 4, an electronicsubstrate 21 may include a semiconductor material such as silicon (Si),gallium arsenide (GaAs), silicon germanium (SiGe), and/or sapphire. Moreparticularly, the electronic substrate 21 may include a plurality ofelectronic devices such as transistors, diodes, resistors, capacitors,and/or inductors, providing a defined functionality. In addition, aconductive input/output pad 27 (such as a copper and/or aluminum pad)may provide electrical connectivity for electrical circuitry of thesubstrate 21. An insulating passivation layer 24 may include aninorganic layer 23 (such as a layer of silicon oxide, silicon nitride,and/or silicon oxynitride) and an organic layer 25 (such as a layer ofbenzocyclobutene BCB and/or polyimide). In an alternative, theinsulating passivation layer 24 may include only one of an inorganiclayer or an organic layer.

As further shown in FIG. 4, a via hole in the insulating passivationlayer 24 may expose portions of the conductive input/output pad 27, anda conductive line 30 may be provided on the insulating passivation layer24. More particularly, the conductive line 30 may include a base layer29 including titanium-tungsten (TiW) and a conduction layer 33 includingaluminum and/or copper. According to particular embodiments of thepresent invention, the conduction layer 33 may include a stack ofaluminum on titanium (Ti/Al), aluminum on titanium on titanium-tungsten(TiW/Ti/Al), copper on titanium (Ti/Cu), copper on titanium-tungsten(TiW/Cu), aluminum on titanium-tungsten on titanium nitride(TiN/TiW/Al), and/or copper on titanium-tungsten on titanium nitride(TiN/TiW/Cu). A conduction layer 33 including a stack of aluminum ontitanium may getter oxygen from a titanium-tungsten base layer.

A second insulating passivation layer 35 on the conductive line 30 andon the first insulting passivation layer 24 includes a second via holetherein exposing a portion of the conductive line 30 offset from theconductive input/output pad 27. Moreover, an under bump metallurgy layer37 and an interconnection structure 39 (such as a solder bump) may beprovided on exposed portions of the conductive line 30. Accordingly, theconductive line 30 may allow redistribution of the interconnectionstructure 39 from the respective conductive input/output pad 27, and theinterconnection structure 39 may provide electrical and/or mechanicalinterconnection to a next level of packaging.

While not shown in FIG. 4, the base layer 29 of the conductive line 30may include a lip extending beyond the conduction layer 33. In additionor in an alternative, portions of the conductive input/output pad 27 maybe exposed between the insulating passivation layer 24 and theconductive line 30. Stated in other words, a width of the conductiveline 30 may be less than a width of portions of the conductiveinput/output pad 27 exposed through the via hole in the insulatingpassivation layer 24.

Methods of forming structures illustrated in FIG. 4 according toembodiments of the present invention are illustrated in FIGS. 1-4. Asshown in FIG. 1, an insulating passivation layer 24 including aninorganic layer 23 (such as silicon oxide, silicon nitride, and/orsilicon oxynitride) and/or an organic layer 25 (such as benzocyclobuteneand/or polyimide) can be formed on a substrate 21. More particularly, aninorganic layer 23 may be formed on the substrate, and an organic layer25 may be formed on the inorganic layer 23 opposite the substrate 21.The substrate 21 may include a material such as silicon (Si), galliumarsenide (GaAs), silicon germanium (SiGe), and/or sapphire, and theelectronic substrate may include electronic devices such as transistors,diodes, resistors, capacitors, and/or inductors.

In addition, a conductive input/output pad 27 (such as an aluminumand/or copper pad) may be included on the substrate 21, and theconductive input/output pad 27 may provide electrical connectivity forcircuitry of the substrate 21. Moreover, a via hole in the insulatingpassivation layer 24 may expose at least a portion of the conductive pad27. As further shown in FIG. 1, a blanket layer of titanium-tungsten 29′may be formed on the insulating passivation layer 24 and on portions ofthe conductive input/output pad 27 exposed through the via hole in theinsulating passivation layer 24.

Prior to forming the blanket layer of titanium-tungsten 29′, the exposedsurface of the conductive input/output pad 27 may be subjected to a wetand/or dry pretreatment to reduce a surface oxide thereof and to reducea contact resistance between the conductive input/output pad 27 and thetitanium-tungsten formed thereon. For example, the exposed surface ofthe conductive input/output pad 27 may be subjected to a sputter clean,and the blanket layer of titanium-tungsten 29′ can be formed bysputtering. Moreover, the sputter clean and the sputter deposition canbe performed in a same process chamber to reduce further oxidationand/or contamination. In alternatives, the exposed surface of theconductive input/output pad 27 may be subjected to a wet etch/clean, adry etch/clean, and/or a plasma etch/clean prior to forming the blanketlayer of titanium-tungsten, and/or the blanket layer oftitanium-tungsten 29 may be formed by evaporation.

More particularly, the blanket layer of titanium-tungsten 29′ may beformed to a thickness of approximately 100 Angstroms. The blanket layerof titanium may have a composition of approximately 10% titanium and 90%tungsten.

With an aluminum conductive input/output pad 27, the blanket layer oftitanium-tungsten 29′ may provide passivation of portions of thealuminum conductive input/output pad 27 exposed through the via hole inthe insulating passivation layer 24. The blanket layer oftitanium-tungsten 29′ may also getter oxygen from the surface of thealuminum conductive input/output pad 27.

As shown in FIG. 2A, a conduction layer 33 may be formed using a using alift-off technique. More particularly, a resist layer 31 may be formedand patterned to provide a lift-off stencil with an opening exposingportions of the blanket layer of titanium-tungsten 29′. A layer of metal33 is then formed on the resist layer 31 and on exposed portions of thetitanium-tungsten (TiW) layer 29. The metal layer 33 may includealuminum and/or copper, and the metal layer 33 may be formed byevaporation. The metal layer 33 may include a stack of metal layers suchas aluminum on titanium (Ti/Al), aluminum on titanium ontitanium-tungsten (TiW/Ti/Al), copper on titanium (Ti/Cu), copper ontitanium-tungsten (TiW/Cu), aluminum on titanium-tungsten on titaniumnitride (TiN/TiW/Al), and/or copper on titanium-tungsten on titaniumnitride (TiN/TiW/Cu). For example, the conduction layer may include atitanium layer having a thickness in the range of approximately 200Angstroms to approximately 1000 Angstroms on the blanket layer oftitanium-tungsten 29′, and an aluminum layer having a thickness ofapproximately 2 μm. A conduction layer 33 including a stack of aluminumon titanium may getter oxygen from a titanium-tungsten base layer.

The structure including the resist layer 31 and the conduction layer 33may then be exposed to a solvent bath so that the resist layer 31dissolves and portions of the metal layer 33 thereon lift off. Portionsof the blank layer of titanium-tungsten (TiW) 29′ not covered by theremaining portions of the metal layer 33 may then be removed using anetch chemistry that selectively etches titanium-tungsten with respect toaluminum and/or copper to provide the structure of FIG. 3 with theconductive line 30 including a base layer of titanium-tungsten 29 and aconduction layer 33. With a conduction layer 33 including a stack ofaluminum on titanium, exposed portions of the blanket layer oftitanium-tungsten 29′ (10% Ti and 90% W) may be etched using an etchingagent such as hydrogen peroxide (H₂O₂) in water (30% H₂O₂), and/or amixture including hydrogen peroxide (H₂O₂), water, potassium sulfate,benzotriazole, and sulfo-salicylic acid.

In an alternative, the conduction layer 33 can be formed usingphotolithography/etch techniques as illustrated, for example, in FIG.2B, and exposed portions of the blanket layer of titanium-tungsten 29′can be removed to provide the structure of FIG. 3. More particularly, ablanket metal layer 33′ including aluminum and/or copper may besputtered on the blanket layer of titanium-tungsten 29′. The blanketmetal layer 33′ may be a stack of metal layers such as aluminum ontitanium (Ti/Al), aluminum on titanium on titanium-tungsten (TiW/Ti/Al),copper on titanium (Ti/Cu), copper on titanium-tungsten (TiN/Cu),aluminum on titanium-tungsten on titanium nitride (TiN/TiN/Al), and/orcopper on titanium-tungsten on titanium nitride (TiN/TiW/Cu). Forexample, the metal layer 33′ may include a titanium layer having athickness in the range of approximately 200 Angstroms to approximately1000 Angstroms on the blanket layer of titanium-tungsten 29′, and analuminum layer having a thickness of approximately 2 μm.

An etch mask 31′ may then be formed on the metal layer 33′. For example,a layer of photoresist may be deposited, exposed, and developed toprovide the etch mask 31′ on the metal layer 33′. Portions of the metallayer 33′ exposed by etch mask 31′ may then be removed using a wetand/or dry etch chemistry suitable to etch aluminum and/or copper toprovide the conduction layer 33. Portions of the blanket layer oftitanium-tungsten 29′ not covered by the remaining conduction layer 33may then be removed using an etch chemistry that selectively etches TiWwith respect to aluminum and/or copper. With a conduction layer 33including a stack of aluminum on titanium, exposed portions of theblanket layer of titanium-tungsten 29′ (10% Ti and 90% W) may be etchedusing an etching agent such as hydrogen peroxide (H₂O₂) in water (30%H₂O₂), and/or a mixture including hydrogen peroxide (H₂O₂), water,potassium sulfate, benzotriazole, and sulfo-salicylic acid.

The etch mask 31′ can be removed after patterning the conduction layer33 and the base layer 29 to provide the structure illustrated in FIG. 3including the conductive line 30. In an alternative, the mask layer 31′may be removed before etching the TiW layer 29′ after etching the metallayer 33′.

Accordingly, the structure of FIG. 3 may be provided using eitherlift-off techniques as discussed above with regard to FIG. 2A orphotolithography techniques as discussed above with regard to FIG. 2B.In either case, a plasma etch may be used to clean up residual metalafter patterning the conduction layer 33 and the TiW base layer 29.

While not shown in FIG. 3, a lip of the titanium-tungsten base layer 29may extend beyond the conduction layer 33 after patterning thetitanium-tungsten base layer 29 using the conduction layer 33 as an etchmask. More particularly, the lip of the titanium-tungsten base layer maybe self-aligned with respect to the conduction layer 33 and extend auniform distance from the conduction layer 33 around a periphery of theconductive line 30. Without being bound to a particular mechanism, theApplicants theorize that electro-chemical properties of the etchingagent in proximity with the conduction layer 33 (such as an aluminumconduction layer) may reduce a reactivity of the etching agent withrespect to the titanium-tungsten in proximity with the conduction layer.

By maintaining a lip of the base layer 29, an undercutting of theconduction layer 33 may be reduced and/or eliminated and a reliabilityof the conductive line may be increased. If the base layer 29 ispatterned in a manner that allows undercutting of the conduction layer33, the resulting undercut region may provide a blind cavity forentrapment of potential corrosives and/or contaminants; the undercutregion may create potential stress concentration points in packageddevices; and/or the undercut region may reduce a bond strength betweenthe conductive line 30 and the insulating passivation layer 24. Byreducing and/or eliminating undercutting, entrapment of corrosivesand/or contaminants can be reduced, creation of stress concentrationpoints may be reduced, and/or bond strengths may be increased.

In addition, the conductive line 30 may be protected with an inorganicand/or organic insulating passivation layer 35 as shown in FIG. 4. Theinsulating passivation layer 35 may include benzocyclobutene (BCB),polyimide, silicon oxide, silicon nitride, and/or silicon oxynitride.Moreover, a via hole in the insulating passivation layer 35 may expose aportion of the conductive line 30, an under bump metallurgy layer 37 maybe formed on exposed portions of the conductive line 30, and aninterconnection structure 39 (such as a solder bump) may be formed onthe under bump metallurgy layer 37. The interconnection structure 39 maybe formed, for example, using one or more bumping processes such asevaporation, electroplating, electro-less plating, and/or screenprinting. Under bump metallurgy layers and solder bumps are discussed,for example, in U.S. Pat. No. 6,492,197 entitled “Trilayer/bilayerSolder Bumps And Fabrication Methods Therefor” to Rinne; U.S. Pat. No.6,392,163 entitled “Controlled-Shaped Solder Reservoirs For IncreasingThe Volume Of Solder Bumps” to Rinne et al; U.S. Pat. No. 6,389,691entitled “Methods For Forming Integrated Redistribution RoutingConductors And Solder Bumps” to Rinne et al.; U.S. Pat. No. 6,388,203entitled “Controlled-Shaped Solder Reservoirs For Increasing The VolumeOf Solder Bumps, And Structures Formed Thereby” to Rinne et al.; U.S.Pat. No. 6,329,608 entitled “Key-Shaped Solder Bumps And Under BumpMetallurgy” to Rinne et al.; and U.S. Pat. No. 5,293,006 entitled“Solder Bump Including Circular Lip” to Yung. The disclosures of theabove referenced patents are incorporated herein in their entirety byreference. Accordingly, the conductive line 30 may provide electricalconnection between the conductive input/output pad 27 and theinterconnection structure 39 that is laterally offset from theconductive input/output pad.

In an alternative, a second conductive line (not shown) may be formed onthe insulating passivation layer 35 and exposed portions of the firstconductive line 30, and a third insulating passivation layer (not shown)may be provided on the second conductive line (not shown) and theinsulating passivation layer 35. A via hole be provided in the thirdinsulating passivation layer exposing portions of the second conductiveline. Accordingly, multiple levels of conductive lines may be used toprovide electrical connection between a conductive input/output pad anda respective interconnection structure. In an alternative or inaddition, one or more levels of conductive lines may be used to provideelectrical connection between two or more conductive input/output pads.

Steps of forming conductive lines according to additional embodiments ofthe present invention are illustrated in FIGS. 5-8. More particularly, atitanium-tungsten (TiW) base enhancement described with respect to FIGS.5-8 may reduce an undercut region that may otherwise be generatedbeneath wiring formed using wet etch process methods. Undercut regionsbeneath microelectronic structures may generally be undesirable becausea reduced base area may reduce bond strength; an undercut region mayprovide a blind cavity for entrapment of potential corrosives andcontaminants; and an undercut may create potential stress concentrationpoints in packaged devices.

According to embodiments of the present invention, a conductive line maybe provided on an insulating passivation layer of an electronic devicewith the conductive line including a conduction layer on a metal baselayer (different than the conduction layer) and the metal base layerbeing between the conduction layer and the insulating passivation layer.More particularly, a lip of the metal base layer may extend beyond edgesof the conductive line. For example, the conduction layer may be a layerof aluminum, and the metal base layer may be a layer oftitanium-tungsten (TiW). More particularly, an aluminum conduction layermay have a thickness of approximately 2 μm, and a TiW base layer mayhave a thickness of approximately 1000 Å. In addition, a Titaniumbarrier layer may be provided between the aluminum wiring layer and theTiW base layer, and the Ti barrier layer may have a thickness in therange of approximately 200 Å to 1000 Å.

Methods of forming conductive lines including conduction layers on metalbase layers according to embodiments of the present invention areillustrated in FIGS. 5-9. As shown in FIG. 5, a substrate 121 mayinclude electronic devices (such as transistors, diodes, resistors,capacitors, and/or inductors) with a conductive input/output pad 127 andan insulating passivation layer 124 thereon. The substrate 121, forexample, may be a silicon substrate, a gallium arsenide (GaAs)substrate, a silicon germanium (SiGe) substrate, and/or a sapphiresubstrate. The insulating passivation layer 124 may include aninsulating organic and/or an insulating inorganic material. Moreparticularly, the insulating passivation layer 124 may includebenzocyclobutene (BCB), polyimide, silicon oxide, silicon nitride,and/or silicon oxynitride. The insulting passivation layer 124 may alsobe patterned to provide a via therein exposing a portion of theconductive input/output pad 127. The conductive input/output pad 127 maybe an aluminum input/output pad.

A blanket layer 129′ of a metal may be formed on the insulatingpassivation layer 124 and on exposed portions of the conductiveinput/output pad 127. For example, a blanket layer of titanium-tungsten(TiW) having a thickness of approximately 1000 Å may be formed on theinsulating passivation layer 124 and on exposed portions of theconductive input/output pad 127. Moreover, the blanket layer oftitanium-tungsten may be formed by sputtering and/or evaporation to havea composition of approximately 10% Ti and 90% W. Moreover, exposedportions of the conductive input/output pad 127 may be pretreated priorto forming the blanket layer 129′ of metal using a wet and/or drypretreatment. A wet and/or dry pretreatment, for example, may be used toreduce a surface oxide on the conductive input/output pad 127 to therebyreduce a contact resistance between the conductive input/output pad 127and the metal of the blanket layer 129′. More particularly, thepretreatment may include sputtering to reduce a surface oxide on theconductive input/output pad 127. In addition or in an alternative, aplasma treatment may be used to clean a surface of the insulatingpassivation layer 124 and/or the conductive input/output pad 127.

As shown in FIG. 6, a lift-off technique can then be used to form apatterned conduction layer. For example, a patterned layer ofphotoresist 131 may expose portions of the blanket layer 129′ of metalwhere a conduction layer 133 is to be provided wherein the conductionlayer includes a metal not included in the metal of the blanket layer129′. For example, the conduction layer 133 may include a layer ofTitanium (Ti) 132 and a layer of aluminum (Al) 134. More particularly,the titanium layer 132 may have a thickness in the range ofapproximately 200 Å to 1000 Å, and the aluminum layer 134 may have athickness of approximately 2 μm. In various alternatives, the conductionlayer 133 may include sequential layers of aluminum on titanium (Ti/Al);aluminum on titanium on titanium-tungsten (TiW/Ti/Al); sequential layersof copper on titanium (Ti/Cu); copper on titanium-tungsten (TiW/Cu);aluminum on titanium-tungsten on titanium nitride (TiN/TiW/Al); and/orcopper on titanium-tungsten on titanium nitride (TiN/TiW/Cu). Aconduction layer 133 including a stack of aluminum on titanium maygetter oxygen from a titanium-tungsten base layer.

As shown, sacrificial portions of the conduction layer 133′ may also beformed on the photoresist 131. The photoresist 131 and sacrificialportions of the conduction layer 133′ thereon can be removed therebyproviding the conduction layer 133 on the blanket layer 129′. While alift-off technique is discussed, the conduction layer 133 may be formedusing conventional photolithography/etch techniques, such as including awet etch through an etch mask.

A wet etch can then be performed on the blanket layer 129′ of metalwithout using a mask other than the conduction layer 133 to provide thebase layer 129 having lips 119 extending beyond the conduction layer133, as shown in FIG. 7. According to particular embodiments of thepresent invention, the metal base layer 129 may be a titanium-tungsten(10% Tl and 90% W) base layer, the conduction layer 133 may includealuminum layer 134 and titanium layer 132, and the wet etch may beperformed using hydrogen peroxide (H₂O₂) in Water (30% H₂O₂). In analternative, the metal base layer 129 may be a titanium-tungsten (10% Tland 90% W) base layer, the conduction layer 133 may include aluminumlayer 134 and titanium layer 132, and the wet etch may be performedusing a mixture of hydrogen peroxide (H₂O₂), water, potassium sulfate,benzotriazle, and sulfo-salicylic acid.

According to embodiments of the present invention, the lip 119 of thebase layer 129 may be formed to extend beyond the conduction layer 133without requiring a mask (other than the conduction layer 133). Byforming the base layer 129 without requiring a mask, the lip 119 may beself-aligned with respect to conduction layer 133 extending a uniformdistance therefrom. The lip 119 may thus reduce undercutting of theconduction layer 133 thereby improving reliability of the resultingstructure. More particularly, the lip 119 may increase an area ofcontact with the insulating passivation layer 124 thereby improvingadhesion therewith. By reducing undercutting, generation of cracks inthe conduction layer 133 may be reduced. Without being bound to aparticular mechanism, the Applicants theorize that electro-chemicalproperties of the etching-agent in proximity with the conduction layer133 (such as an aluminum conduction layer) may reduce a reactivity ofthe etching agent with respect to the titanium-tungsten in proximitywith the conduction layer.

As shown in FIG. 8, a second insulating passivation layer 135 may beformed on the first insulating passivation layer 124, on the conductionlayer 133, and on the lip 119 of the base layer 129. Moreover, a viahole 123 may be provided though the second insulating passivation layer135 thereby exposing a portion of the conduction layer 133.

As shown in FIG. 9, an interconnection structure 139 (such as a solderbump) may be formed on the exposed portion of the conduction layer 133.Accordingly, a conductive line (including the conduction layer 133 andthe base layer 129) may provide redistribution from a conductiveinput/output pad 127 to an interconnection structure 139 (such as asolder bump). Moreover, the second insulating passivation layer 135 mayinclude an organic and/or an inorganic insulating material. Moreparticularly, the second insulating passivation layer may includebenzocyclobutene (BCB), polyimide, silicon oxide, silicon nitride,and/or silicon oxynitride. In an alternative, the conductive line(including conduction layer 133 and base layer 129) may provideinterconnection between the conductive input/output pad 127 and anothercontact pad on the substrate 135.

Various structures including TiW base layers and Al wiring layersaccording to embodiments of the present invention are illustrated in thephotographs of FIGS. 10-13. As shown in the top view of FIG. 10, aconductive structure may be provided on an insulating passivation layer235, and the conductive structure may include an aluminum conductionlayer 234 on a titanium-tungsten base layer so that thetitanium-tungsten base layer is between the aluminum conduction layer234 and the insulating passivation layer 235. Moreover, a lip 219 of thetitanium-tungsten base layer extends beyond the aluminum conductionlayer 234 a relatively uniform distance around the periphery of theconductive structure. As shown, the conductive structure may haveelongate and enlarged width portions.

FIG. 11 is a top view of additional conductive structures on aninsulating passivation layer 335 according to embodiments of the presentinvention. As shown in FIG. 11, aluminum conduction layers 334 may beprovided on respective titanium-tungsten base layers such that lips 319of the titanium-tungsten base layers extend beyond the aluminumconduction layers 334 around the periphery of the conductive structures.

FIG. 12 is a top view of still additional conductive structures on aninsulating passivation layer 435 according to embodiments of the presentinvention. As shown in FIG. 12, an aluminum conduction layer 434 may beprovided on a respective titanium-tungsten base layer such that a lip419 of the titanium-tungsten base layer is extends beyond the aluminumconduction layer 434 a relatively uniform distance around the peripheryof the conductive structure.

FIG. 13 is a photograph of a cross-section of a conductive structureaccording to embodiments of the present invention. As shown in FIG. 13,the conductive structure may be formed on an insulating passivationlayer 535, and the conductive structure may include a titanium-tungstenbase layer 529 and an aluminum conduction layer 534. More particularly,the titanium-tungsten base layer 529 may include a lip 519 extendingbeyond the aluminum conduction layer 534.

In the drawings and specification, there have been disclosed typicalpreferred embodiments of the invention and, although specific terms areemployed, they are used in a generic and descriptive sense only and notfor purposes of limitation, the scope of the invention being set forthin the following claims.

1. An electronic device comprising: a substrate; a conductive pad on thesubstrate; an insulating layer on the substrate, the insulating layerhaving a via hole therein exposing a portion of the conductive pad; aconductive structure on the insulating layer and on the exposed portionof the conductive pad, the conductive structure including a base layercomprising titanium-tungsten (TiW) and a conduction layer comprising atleast one of aluminum and/or copper, wherein the base layer of theconductive structure is between the conduction layer and the insulatinglayer.
 2. An electronic device according to claim 1 wherein the baselayer of the conductive structure includes a lip extending beyond theconduction layer of the conductive structure.
 3. An electronic deviceaccording to claim 1 wherein the conductive pad comprises at least oneof aluminum and/or copper.
 4. An electronic device according to claim 1further comprising: a second insulating layer on the conductivestructure and on the first insulating layer so that the conductivestructure is between the first and second insulating layers, the secondinsulating layer having a second via hole therein exposing a portion ofthe conductive structure wherein the first and second via holes areoffset.
 5. An electronic device according to claim 4 further comprising:an interconnection structure on the exposed portion of the conductivestructure.
 6. An electronic device according to claim 5 furthercomprising: an under bump metallurgy layer between the interconnectionstructure and the exposed portion of the conductive structure.
 7. Anelectronic device according to claim 5 wherein the interconnectionstructure comprises solder.
 8. An electronic device according to claim 1wherein the conduction layer of the conductive structure comprises analuminum layer.
 9. An electronic device according to claim 8 wherein theconduction layer of the conductive structure further comprises atitanium layer between the aluminum layer and the base layer of theconductive structure.
 10. An electronic device according to claim 1wherein a portion of the conductive pad is exposed between theinsulating layer and the conductive structure.
 11. An electronic deviceaccording to claim 1 wherein the insulating layer comprises at least oneof benzocyclobutene, polyimide, silicon oxide, silicon nitride, and/orsilicon oxynitride.
 12. An electronic device comprising; a substrate; aninsulating layer on the substrate; a conductive structure on theinsulating layer, the conductive structure including a base layercomprising titanium-tungsten (TiW) and a conduction layer comprising atleast one of aluminum and/or copper, wherein the base layer of theconductive structure is between the conduction layer and the insulatinglayer, and wherein the base layer of the conductive structure includes alip extending beyond the conduction layer of the conductive structure.13. An electronic device according to claim 12 further comprising: aconductive pad on the substrate wherein the insulating layer has a viahole therein exposing a portion of the conductive pad, and wherein aportion of the conductive structure is on the exposed portion of theconductive pad.
 14. An electronic device according to claim 13 whereinthe conductive pad comprises at least one of aluminum and/or copper. 15.An electronic device according to claim 13 wherein a portion of theconductive pad is exposed between the insulating layer and theconductive structure.
 16. An electronic device according to claim 12further comprising: a second insulating layer on the conductivestructure and on the first insulating layer so that the conductivestructure is between the first and second insulating layers, the secondinsulating layer having a second via hole therein exposing a portion ofthe conductive structure.
 17. An electronic device according to claim 16further comprising: an interconnection structure on the exposed portionof the conductive structure.
 18. An electronic device according to claim17 further comprising: an under bump metallurgy layer between theinterconnection structure and the exposed portion of the conductivestructure.
 19. An electronic device according to claim 17 wherein theinterconnection structure comprises solder.
 20. An electronic deviceaccording to claim 12 wherein the conduction layer of the conductivestructure comprises an aluminum layer.
 21. An electronic deviceaccording to claim 20 wherein the conduction layer of the conductivestructure further comprises a titanium layer between the aluminum layerand the base layer of the conductive structure.
 22. An electronic deviceaccording to claim 12 wherein the insulating layer comprises at leastone of benzocyclobutene, polyimide, silicon oxide, silicon nitride,and/or silicon oxynitride.
 23. An electronic structure comprising: asubstrate including a conductive pad thereon; a passivation layer on thesubstrate, the passivation layer having a via hole therein exposing aportion of the conductive pad; and a redistribution wiring line on thepassivation layer and on the exposed portion of the conductive pad, theredistribution wiring line including a first layer comprising TiW and asecond layer comprising at least one of aluminum and copper.
 24. Anelectronic structure according to claim 23, further comprising: a secondpassivation layer on the redistribution wiring line, the secondpassivation layer having a second via hole therein exposing a portion ofthe redistribution wiring line; an underbump metallurgy layer on theexposed portion of the redistribution wiring line; and a solder bump onthe underbump metallurgy layer.
 25. An electronic device comprising: asubstrate having an insulating layer thereon; a metal base layer on aportion of the insulating layer wherein portions of the insulating layerare free of the metal base layer; and a metal wiring layer on the metalbase layer wherein the metal wiring layer comprises a metal not includedin the metal base layer, wherein the metal base layer is between themetal wiring layer and the insulating layer, and wherein the metal baselayer includes a lip extending beyond the metal wiring layer.
 26. Anelectronic device according to claim 25 wherein the metal base layercomprises titanium-tungsten.
 27. An electronic device according to claim26 wherein the metal wiring layer comprises an aluminum layer.
 28. Anelectronic device according to claim 27 wherein the metal wiring layerincludes a titanium layer between the aluminum layer and the metal baselayer.
 29. A method of forming an electronic device, the methodcomprising: forming a continuous metal base layer on an insulatinglayer; forming a metal wiring layer on a portion of the continuous metalbase layer so that portions of the continuous metal base layer are freeof the metal wiring layer and so that the continuous metal base layer isbetween the metal wiring layer and the insulating layer; and removingportions of the continuous metal base layer free of the metal wiringlayer to provide a patterned metal base layer between the metal wiringlayer and the insulating layer wherein the patterned metal base layerincludes a lip extending beyond the metal wiring layer.
 30. A methodaccording to claim 29 wherein the continuous metal base layer ismaintained free of a mask other than the metal wiring layer whileremoving portions of the continuous metal base layer.
 31. A methodaccording to claim 29 wherein the continuous metal base layer comprisestitanium-tungsten.
 32. A method according to claim 31 wherein the metalwiring layer comprises an aluminum layer.
 33. A method according toclaim 32 wherein the metal wiring layer includes a titanium layerbetween the aluminum layer and the metal base layer.